Field of the Invention
The disclosure relates generally to performance management methods and related electronic devices, and, more particularly to performance management methods for an electronic device with multiple central processing units.
Description of the Related Art
Central processing unit (CPU) hot-plug is an operating system mechanism that plugs in one power-gated or power-collapsed CPU, or unplugs one unused CPU. Particularly, on portable devices such as mobile devices, CPU hot-plug is an importance key feature to save battery life.
When determining to plug in one CPU or to unplug it, it is considered not only save power but also retain overall system performance. In most designs, frequently-used factors to determine hot-plugging consist of current CPU frequency, CPU usage, the number of running threads, and so on. However, all of them lack the capability of reflecting what would actually happen after hot-plugging. For example, after plugging in one CPU, if just a thread with a small loading is offloaded to the plugged CPU, the newly-plugged CPU may stay at an idle state for most of the time. In such a case, however, the CPU hot-plug decision by plugging in one CPU gains little performance benefit, whereas it brings much harm to power. It is absolutely a bad trade-off.